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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
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    <title>Document</title>
    <script>
        function User(name,pass){
            this.name = name;
            this.pass = pass;
        }
        User.prototype.showName = function(){
            console.log(this.name);
        }
        User.prototype.showPass = function(){
            console.log(this.pass);
        }
        
        function VipUser(name,pass,level){
            User.call(this,name,pass);
            this.level = level
        }

        VipUser.prototype = new User();
        VipUser.prototype.constructor = VipUser;
        VipUser.prototype.showLevel = function(){
            console.log(this.level);
        }

        let vipUser = new VipUser('lan',324,3);
        vipUser.showName();
        vipUser.showPass();
        vipUser.showLevel();

    </script>
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<body>
    
</body>
</html>